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Register a new userExtrinsic photonic crystals
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Doped semiconductors are intrinsically homogeneous media. However, by applying an external magnetic field that has a spatially periodic variation, doped semiconductors can behave extrinsically like conventional photonic crystals. We show this possibility theoretically by calculating the photonic band structures of a doped semiconductor under an external, spatially periodic magnetic field. Homogeneous media, behaving like conventional photonic crystals under some external, spatially periodic fields, define a new kind of photonic crystals: extrinsic photonic crystals. The proposed extrinsic photonic crystals could not only extend the concept of photonic crystals but also lead to the control of the dispersion and propagation of electromagnetic waves in a unique way: simply manipulating the externally applied fields.
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We study wave propagation and diffraction in a bidimensional photonic crystal with finite height, in case where the wavelength is large with respect to the period of the structure. The device is made of materials with anisotropic permittivity and permeability tensors. We derive rigorously the homogenized system, using the concept of two-scale convergence. The effective permittivity and permeability tensors turn out to be that of a two-dimensional photonic crystal with infinite height.
We solve {bf analytically} the multiple scattering (KKR) equations for the two dimensional photonic crystals in the long wavelength limit. Different approximations of the electric and magnetic susceptibilities are presented from a unified pseudopotential point of view. The nature of the so called plasmon-polariton bands are clarified. Its frequency as a function of the wire radius is discussed.
The complete symmetry characterization of eigenstates in bare opal systems is obtained by means of group theory. This symmetry assignment has allowed us to identify several bands that cannot couple with an incident external plane wave. Our prediction is supported by layer-KKR calculations, which are also performed: the coupling coefficients between bulk modes and externally excited field tend to zero when symmetry properties mismatch.
Magnetooptical properties of magnetic photonic crystals have been investigated in the view of their possible applications for the modern integrated-optics devices. A transfer matrices formalism was expanded for the case of oblique light incidence on the periodic nanoscaled magnetic multilayered systems. Several new effects such as the Faraday effect dependence on the incidence angle and the tunability of the bandgap defect modes spectral location by external magnetic fields were found. Several possibilities of one-dimensional magnetic photonic crystals applications for the optical devices are discussed. Initial steps towards the practical implementation of the proposed devices are reported.
We have investigated multifunctional periodic structures in which electromagnetic waves and spin waves can be confined in the same areas. Such simultaneous localization of both sorts of excitations can potentially enhance the interaction between electromagnetic waves and spin waves. The system we considered has a form of one dimensional photonic-magnonic crystal with two types of magnetic layers (thicker and thinner ones) separated by sections of the dielectric photonic crystals. We focused on the electromagnetic defect modes localized in the magnetic layers (areas where spin waves can be exited) and decaying in the sections of conventional (nonmagnetic) photonic crystals. We showed how the change of relative thickness of two types of the magnetic layers can influence on the spectrum of spin waves and electromagnetic defect modes, both localized in magnetic parts of the system.
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